In a field of wound medicine research or the like, the storage and transportation of samples has been carried out by sealing or encapsulating a sample-dissolved solution into a tube case so called as a microtube and accommodating a plurality of microtubes in a vertically provided manner in a storage rack which is partitioned in a grid pattern, for example partitioned into 96 receptacles in a matrix with 8 rows and 12 columns. Further, to accommodate smaller microtubes that is ultramicrotubes (hereinafter sometimes referred to as “384 tube”) in the same size storage rack as a storage rack partitioned into 96 sections in accordance with a standard of SBS (Society for Biomolecular Screening) a storage rack with the total of 384 partitioned sections in a matrix with 16 rows and 24 columns has been also known [(see for example, European Patent Application Publication No. 0904841 (FIG. 1, paragraphs 7 to 9) and European Patent Application Publication No. 1477226 (FIG. 5, paragraphs 3 to 5) and related U.S. Pat. No. 6,827,907].
FIG. 8 shows a samples storage system 800 for pharmaceutical development for accommodating ultramicrotubes (or 384 tubes) described in European Patent Application Publication No. 0904841. In this samples storage system 800 for pharmaceutical development, in a storage rack 810 with the same size as the storage rack in accordance with an SBS standard, in which 96 tubes are accommodated, it is four times number of tubes, that is 384, tubular ultramicrotubes 820 with bottoms are accommodated. Thus since the above-mentioned ultramicrotubes 820 take a shape in which a bottom surface size of a the ultramicrotubes (384 tubes) was reduced to substantially ¼ of the surface size of the microtubes (96 tubes), the capacity of samples to be accommodated must be decreased. Further, since engagement partition walls 816 for forming accommodation sections 813 partitioned in a matrix with 16 rows and 24 columns are formed at substantially the same height as a rack frame 814 of the storage rack 810, an accommodation region in the ultramicrotubes 820 is decreased by the thickness of these engagement partition walls 816 and the capacity of samples to be accommodated was even more restricted as compared with the microtubes (96 tubes).
FIG. 9 shows a partial cross-sectional view of a samples storage system 900 for pharmaceutical development accommodating ultramicrotubes described in European Patent Application Publication No. 1477226. In this samples storage system 900 for pharmaceutical development, a storage rack 910 accommodates four times number of tubes, that is ultramicrotubes 920, is the same size storage rack 910 as a storage rack in accordance with the SBS standard, accommodating microtubes (96 tubes) like the conventional case shown in FIG. 8. Since the ultramicrotubes 920 in this storage rack 910 have a rectangular hollow tubular cross-section, the storage rack 910 has a greater accommodation volume than the tubular ultramicrotubes shown in FIG. 8.
However, since in this storage rack 910, engagement partition walls 916 extend to shoulder portions 922 of ultramicrotubes 920 and corner portions of the outer surfaces of the ultramicrotubes have chamfered portions (not shown), slight gaps are formed at corner portions of an accommodation portion 913 whose top are a square, resulting in a reduced increase in the accommodation volume by reason of the gaps. Further, since one surface or two surfaces of the respective tubes 920 accommodated adjacent the frame are supported against frame side walls 918, which are unlikely to elastically deform, the tubes 920 are difficult to insert and extract. Further, since there are differences in forces required for insertion and extraction between a case of tubes at the center portion of the storage rack and a case of tubes near the rack side wall 918, a complex control is required when picking with an automatic picking device.